add app links for students and org history

student_app.md

+Application Checklist for Purr Data GSoC Students
+-------------------------------------------------
+
+* show us links to any open source projects you've created, or any commits you've made to open source projects
+* explain which parts of the code will be affected by your project
+* schedule for how you plan to break up the project and complete it over the course of the summer
+* make sure to include an initial goal for the first week that is specific, self-contained, and fairly straightforward to successfully complete